Fix #257 (#258)

* Fix #257

* Bump version from 0.15.11 to 0.15.12

Author: dlfivefifty

Project.toml

@@ -1,6 +1,6 @@
 name = "ClassicalOrthogonalPolynomials"
 uuid = "b30e2e7b-c4ee-47da-9d5f-2c5c27239acd"
-version = "0.15.11"
+version = "0.15.12"
 authors = ["Sheehan Olver <[email protected]>"]
 
 [deps]

src/clenshaw.jl

@@ -139,5 +139,5 @@ _broadcasted_layout_broadcasted_mul(_, wv, P) = layout_broadcasted(nothing, *, w
 # constructor for Clenshaw
 function Clenshaw(a::AbstractQuasiVector, X::AbstractQuasiMatrix)
     P,c = arguments(a)
-    Clenshaw(paddeddata(c), recurrencecoefficients(P)..., jacobimatrix(X), _p0(P))
+    Clenshaw(paddeddata(c), recurrencecoefficients(P)..., jacobimatrix(X), convert(promote_type(eltype(a), eltype(X)), _p0(P)))
 end

test/test_ultraspherical.jl

@@ -218,4 +218,13 @@ using ClassicalOrthogonalPolynomials: grammatrix
             @test lhs ≈ rhs
         end
     end
+
+    @testset "Issue #257" begin
+        T = chebyshevt(0 .. 1) # solution basis is T_n 
+        C = ultraspherical(1, 0 .. 1) # RHS basis is C_n^(2)
+        s = axes(T, 1)
+
+        op = (s .+ im) .* T
+        @test (C \ op)[1,1] ≈ 0.5 + im
+    end
 end